标题： 细胞分裂在果蝇胚胎中既挑战又完善组织边界 显示英文标题

标题： Cell divisions both challenge and refine tissue boundaries in the Drosophila embryo

摘要： 组织边界塑造胚胎，抑制肿瘤，并提供方向性线索。 组织边界与由肌动蛋白和非肌肉肌球蛋白II形成的超细胞束有关。 肌动蛋白-肌球蛋白束产生张力，防止细胞混合。 其他细胞行为是否参与细胞群体之间线性界面的形成仍不清楚。 在果蝇胚胎中，一种基于肌动蛋白-肌球蛋白的边界将外胚层与中胚层外胚层分开，后者是一组神经元和胶质祖细胞。 数学建模预测，外胚层中的细胞分裂会挑战中胚层外胚层（ME）边界。 与此一致的是，在体内抑制外胚层细胞分裂可以阻止在失去基于肌动蛋白-肌球蛋白的张力时跨ME边界的细胞混合。 我们的数学模型还预测，通过减少外胚层的张力并增加细胞运动性，细胞分裂使ME边界更加清晰。 我们发现，在体内抑制外胚层分裂会降低边界的线性度。 使用激光消融和细胞追踪，我们证明细胞分裂减少了外胚层的连接张力并增加了细胞运动。 总的来说，我们的结果揭示了细胞分裂通过促进细胞重排以增加流体性，从而在一种新的边界精修机制中发挥作用。 显示英文摘要

摘要： Tissue boundaries pattern embryos, suppress tumours, and provide directional cues. Tissue boundaries are associated with supracellular cables formed by actin and the molecular motor non-muscle myosin II. Actomyosin cables generate tension that prevents cell mixing. Whether other cellular behaviours contribute to the formation of linear interfaces between cell populations remains unclear. In the Drosophila embryo, an actomyosin-based boundary separates the ectoderm from the mesectoderm, a group of neuronal and glial progenitors. Mathematical modelling predicted that cell divisions in the ectoderm challenge the mesectoderm-ectoderm (ME) boundary. Consistent with this, suppressing ectoderm cell divisions in vivo prevented cell mixing across the ME boundary when actomyosin-based tension was lost. Our mathematical model also predicted that cell divisions sharpen the ME boundary by reducing tension and increasing cell motility in the ectoderm. We found that inhibiting ectoderm divisions in vivo reduced boundary linearity. Using laser ablation and cell tracking, we demonstrated that cell divisions reduced junctional tension and increased cell movement in the ectoderm. Together, our results reveal that cell divisions facilitate cellular rearrangements to increase fluidity in a novel mechanism for boundary refinement.